A study published in the journal *mSystems* explores the diversity of Gardnerella species and clades in the vaginal microbiome of pregnant women and their potential impact on premature delivery.
Gardnerella and Vaginal Health
Certain species in the vaginal microbiome, like Gardnerella, are linked to health issues such as sexually transmitted diseases, cervical cancer, premature delivery, and bacterial vaginosis. Gardnerella produces sialidase, an enzyme that breaks down protective mucins in the vagina, leading to increased inflammation. Despite this, Gardnerella can exist in varying amounts without causing symptoms or disease.
Study Overview
Researchers developed a computer technique to identify Gardnerella clades and species in vaginal microbiomes and assess their abundance in relation to preterm births. They analyzed samples from pregnant women in several cohorts: the Multi-Omic Microbiome Study: Pregnancy Initiative (MOMS-PI), UAB-enriched, and Stanford-enriched, totaling 888 samples from 266 individuals. An additional cohort included 145 samples from 42 individuals to match Gardnerella abundance distributions.
The new method identified six clades comprising 14 genomic species in vaginal swabs. The study examined whether different Gardnerella clades during pregnancy were linked to preterm delivery risk, and analyzed Gardnerella abundance in the vaginal microbiome.
Key Findings
Researchers found that individual microbiomes often contained multiple Gardnerella variations. The number of clades was directly proportional to microbial burdens, suggesting a link between Gardnerella abundance and preterm birth risk.
The study observed consistent taxon co-occurrences among Gardnerella clades and identified previously uncommon variations in additional cohorts, highlighting the importance of studying diverse populations to capture Gardnerella diversity.
A core-genome phylogeny of Gardnerella was constructed, revealing 85 core genes among 12,105 pangenome genes. Gardnerella had a median relative abundance of 17% in unenriched and 45% in enriched MOMS-PI cohorts. The study confirmed 14 Gardnerella genomic species and six clades, with the first through fourth clades being more common than the fifth and sixth. The third clade was particularly prevalent among African American individuals.
Implications
The presence of diverse Gardnerella variants in vaginal microbiomes indicates high species diversity. The number of clades correlated with higher microbial load, potentially linking Gardnerella diversity to microbiota composition and preterm birth risk.
The study underscores the need for further research to understand Gardnerella’s ecological roles, interactions within microbial ecosystems, and their impact on health outcomes, particularly in relation to preterm births.
